Journal of Biological Control, 30(4): 198-209, 2016, DOI: 10.18311/jbc/2016/15565 Review Article Recent trends in biological control of scale insects on fruit crops in India M. MANI* Former Head, Division of Entomology, Nematology, Indian Institute of Horticultural Research, Bangalore - 560 089, Karnataka, India *Corresponding author E-mail: [email protected] ABSTRACT: Scale insects are sap feeders, causing threat to the cultivation of several fruit crops. The scale insects can be grouped into two broad categories. The first group belonging to family Diaspidide, comprises many species of armoured scales (hard scales) belonging to the genera. Aonidiella, Aulacaspis, Pseudaulacaspis, Hemiberlesia, Aspidiotus, Chrysomphalus, Pinnaspis, Parlatoria etc. The second category belonging to family Coccidae comprises of the soft scales belonging to the genera Coccus, Puvinaria, Chloropulvinaria, Saiset- tia, Parasaisettia, Vinsonia, Drephanococcus, Ceroplastes, Ceroplastodes, etc. Scale insects are highly polyphagous, but certain species cause severe damage to specific fruit crops viz. the red scale,Aonidiella aurantii (Maskell) on citrus; latania scale, Hemieberlesia lataniae (Sign.) on grapevine.; white scale, Aulacaspis tubercularis (Newstead) on mango; green shield scale, Pulvinaria psidii (Maskell) on guava, lemon and sapota, Pulvinaria polygonata (Ckll.) on mango; green scale Coccus viridis (Green) on citrus and sapota and Drephano- coccus chiton (Green) on ber and guava. Insecticides are not effective due to the presence of protective cover over the scales. On the other hand, scale insects are more amenable for biological control due to their sedentary habit and colonial distribution. Several scale insects are well regulated by the local predators. In nature, green shield scale, Pulvinaria psidii (Maskell) is kept under check by the predator, Australian ladybird beetle Cryptolaemus montouzieri Mulsant on guava, sapota and lemon. The reduction of the mango green shield scale Pulvinaria polygonata was attributed mainly to the action of the predators C. montrouzieri and Spalgis epeus Westwood. The green scale Coccus viridis on acid lime and white scale Aulacaspis tubercularis on mango are well regulated by the coccinellids Chilocorus nigrita (Fab) and C. circumdatus Sch. Local parasitoids are also known to effectively check the populations of the scale insects on different fruit crops. The encyrtid Anicetus ceylonensis How and the pteromalid Cephaleta brunniventris Motsch are responsible for the suppression of wax scale Drephanococcus chiton on ber and guava. The aphelinid parasitoid, Pteroptrix koebeli How. plays a major role in the regulation of the mango scale Aulacaspis tubercularis. On sapota, the aphelinid parasitoid Coccophagus sp. was the dominant natural enemy caus- ing up to 95 % parasitism. Scutellista cyanea Motsch. (Pteromalidiae: Hymenoptera) was able to suppress Parasaissetia nigra (Nietner) on custard apple and pomegranate. In the absence of effective biocontrol agents in nature, parasitoids and predators have to be released in the field for obtaining an effective and quicker suppression of the scale insects. Release of adult C. nigirita was found to be effective in the control of the red scale on citrus in Karnataka, Andhra Pradesh and Punjab. Release of C. infernalis (C.bijugus) Mulsant @ 10-20 beetles/tree once in April-May has also been recommended to reduce Sanjose scale. The white halo fungus, Lecanicillium (Verticillium ) lecanii can be sprayed at 16 x 106 spores/ml along with 0.05% of sticking agents in the evening hours at 15 days interval to control the green scale in the hilly areas during cooler months. The biocontrol agents can be integrated with plant origin insecticides as they do not affect the activity of these agents. KEY WORDS: Biological control, fruit crops, hard scales, predator, parasitoids, scale insects, soft scales (Article chronicle: 22-12-2016; Revised: 28-12-2016; Accepted: 28-12-2016) INTRODUCTION and are usually larger, lack the protective cover, but protect themselves with waxy secretions. Scale insects are suck- Scale insects get their name because the females se- ing insects laying their the eggs underneath the hard scale crete a waxy covering that gives them the appearance of a covering or in an ovisac covered with filamentous secre- fish scale. They are tiny insects varying in colour. Scale in- tion, making difficult to get killed with conventional chemi- sects are a diverse group of insects in the order Hemiptera, cals (Maniand Krishnamoorthy, 2001). Nymphs and adult superfamily coccoidea. Scale insects can be broadly divided female scale insects become immobile /sedentary/sessile. into two groups: armored scales (Diapididae) and soft scales They are easily available /susceptible throughout the year to (Coccidae). Armoured scales secrete a protective cover over the attack by the parasitoids and predators. In fact, the first their bodies.The soft scales are usually half round rubbery 198 MANI outstanding biocontrol success was the complete suppres- Biological control of diaspine/hard scales sion of the cottony cushion scale Icerya purchasi Maskell San Jose Scale - Quadraspidiotus perniciosus with the predator Rodolia cardinalis Mulsant was on citrus fruits ((Bartlett, 1978). Quadraspidiotus perniciosus (Comstock) is seri- ous pest of many temperate fruits in Jammu & Kashmir, Hard scales (Armoured Scale Insects, Diaspine scales) Himachal Pradesh and Uttaranchal. The first signs of infes- Armoured scales are formed from the waxy filaments tation include a decline of tree vigor, leaf drop and appear- that the insect secretes as it rotates its body in a circular ance of sparse yellow foliage, particularly on the terminal pattern. Armoured scales are the smallest of scale insects, growth. Reddish spots on the underside of bark and around ranging in size from 1 to 3 mm. The body of the scale insect scales on leaves or fruit result from feeding of immature is protected by a cover (the armour) made from wax secret- stages. In severe cases, the entire surface of bark can be- ed by the insect and cast skins (exuviae) of previous growth come covered with layers of overlapping grayish scales. stages. The exposed body usually is yellow or orange, but Cracking and bleeding of limbs occur and heavily injured may have a pink or red colour to it. This cover also protects trees may die. The aphelinid parasitoid Encarsia perniciosi the eggs laid by the female. Adult armored scales are usu- (Tower) was introduced in 1953 into India (Rao and Rao, ally protected from chemicals because of their protective 1960). The Russian strain of E. perniciosi proved satisfac- shell (Rosen, 1990). The hard scales belonging to family tory in H.P. while Chinese, American and Illinois strains Diaspidide, comprises many species belonging to the gen- performed much better in U.P. (Sahai and Joshi, 1965). In re- era viz. Aonidiella, Aulacaspis, Pseudaulacaspis, Hemiber- cent years, the pest has appeared in severe form mainly due lesia, Aspidiotus, Chrysomphalus, Pinnaspis, Parlatoria to the interference of insecticidal applications. Augmenta- etc. Among them, Calfornia red scale Aonidiella aurantii tive release of E. perniciosi / Aphytis sp. (proclia group)/ is found highly destructive to citrus in India causing heavy Aphytis diaspidis (How.)@ 2,000 adults / infested tree once loss to citrus growers. San Jose scale - Quadraspidiotus per- in spring is recommended to suppress the scale. Release of niciosus (Comstock) serious pest of many temperate fruits Aphytis sp. (proclia group) had resulted in 60-70% parasit- in Jammu & Kashmir, Himachal Pradesh and Uttaranchal. ism in Kullu (H.P) (Thakur et al., 1989) and 40.2 % in J&K Aulacaspis tubercularis and Aspidiotus destructor Signoret (Masoodi et al., 1989). Coccinellid predators Chilocorus are well known to cause damage to mango. (Table 1) infernalis Mulsant and Pharoscymnus flexibilis (Mulsant) Table 1. List of hard scales infesting fruit crops in India Aonidiella citrina (Coquillett) Citrus, custard apple, mango, date palm Aonidiella orientalis (Newstead) Banana, ber, citrus, guava, jamun, peach, pomegranate, mango Aspidiotus destructor Signoret Banana, ber, citrus, guava, jamun, peach, pomegranate, fig, pear, mango, sapota, apple, papaya, grapes Octaspidiotus tripurensis Takagi Mango Aulacaspis tubercularis Newstead Mango, citrus Chrysomphalus aonidum (L.) (= Chrysomphalus ficus Ashmead) Citrus, mango, almond, banana, guava, grapes, date palm Chrysomphalus dictyosperni (Morgan) Citrus, banana, mango, apple Hemiberlesia lataniae (Sign.) Apple, jack fruit, sapota, ber, grapes, plum, peach, citrus, ba- nana, guava, mango Howardia biclavis (Comstock) Sapota, peach, apple, ber, citrus, custard apple Lepidosaphes (=Corunaspis) beckii (Newman) Citrus Parlatoria blanchardi (Targioni Tozzetti) Date palm Parlatoria cinerea Hadden Apple, apricot, citrus, phalsa, jamun, litchi, mango, peach, plum Parlatoria oleae (Colvée) Mango, ber, apricot, pomegranate, peach, apple, citrus, fig, grapes, pear, plum, apple Purgatorial pergandii Comstock Citrus, guava, mango Pinnaspis strachani Signoret Date palm, citrus, banana Pinnaspis aspidistrae Signoret Citrus, fig, jack fruit, mango Pseudaulacaspis rubra (Maskell) (=Pseudaulacaspis bar- Mango beri (Green)) Pseudaulacaspis pentagona (Targioni) Apple, cherry, peach, plum, pear Quadraspidiotus perniciosus (Comstock) Apple, citrus, cherry, peach, plum, pear, raspberry, strawberry Chlidaspis asiatica (Archangelskaya) Apple and plum 199 Recent